There is a need in the art for a low cost, high strength, high performance steel composition. Such high strength, high performance steels have various applications in both the commercial and military industries. For example, commercial applications of high strength, high performance steels include the following: pressure vessels; hydraulic and mechanical press components; commercial aircraft frame and landing gear components; locomotive, automotive, and truck components, including die block steels for manufacturing of components; and bridge structural members. Exemplary military applications of high strength, high performance steels include hard target penetrator warhead cases, missile components including frames, motors, and ordnance components including gun components, armor plating, military aircraft frame and landing gear components.
One major disadvantage in the use of high strength, high performance steels in such applications is the relatively high cost of the steel, which is the result of the high alloy content and expensive related manufacturing processes associated with such high strength steels. To produce a high strength steel, prior art compositions have included high levels of nickel, which is an expensive element and contributes to the high overall cost of the final steel product. One prior art composition commonly designated as AF-1410, described in U.S. Pat. No. 4,076,525 hereby incorporated by reference, provides a high strength, high performance steel at an expensive cost due to the high weight percentage of nickel, which comprises about 9.5 to about 10.25 percent by weight of the entire AF-1410 steel composition. A need, therefore, exists for an improved low alloy, high strength, high performance steel composition that can be produced relatively inexpensively.
The present invention overcomes the existing need in the prior art by providing a low alloy, low to medium carbon content, and low nickel content steel composition, which exhibits the same desirable high performance characteristics of high strength steel compositions known in the prior art and which can be produced according to current “state-of-the-art” production techniques at substantially lower cost (ladle melting and refining versus vacuum melting and refining). The low carbon and low alloy content makes the steel composition of the present invention more easily welded and more easily heat-treated. Current bomb case materials are not generally weldable, whereas the bomb case material disclosed herein welds very easily. Weldability will increase the options for manufacturing bomb cases and, as a result, should significantly reduce overall production costs for this type of application.
The steel composition of the present invention has utility wherever high strength, high performance steel is desired. The low alloy, high strength steel composition of the present invention is particularly useful in projectile penetrator applications wherein high impact velocities, such as those greater than 1000 feet per second, are imparted to the projectile to cause deep penetration of rock and concrete barriers. The strength, toughness and wear resistance of the steel produced according to the present invention provides enhanced penetrator performance, while at the same time reduces manufacturing costs by using less of the more costly alloy materials such as nickel.